Some of my raw food fanatical friends don't understand this but I always cook carrots before adding to smoothies because carotenoids are more bioavailable that way. Since I have fair skin I also cook celery to reduce the toxin psoralen. If you don't cook it the chemical can makes your skin more sensitive to UV rays. Pineapple core has a bunch of bromelain, but have never tried it.

Some other things that are great in smoothies include cooked sweet potato (I peel it, slice it, microwave until tender, mash it and freeze in cubes) raw squash, cantaloupe seeds, grapes with seeds (only attempt those last two if you have a powerful blender like a Vita Mix or Blend Tec), strawberries with steams and leaves, watermelon rind, raw avocado and ESPECIALLY raw and spinach. You will never be able to tell that there is spinach in your drink aside from the color.If that bothers you then Welch's 100% frozen juice concentrate (with the yellow lid) can mask it.

Other things I like to add at different times are golden flax seeds (ground to order), medjool dates, hemp seed, olive oil, and sometimes chia seed. Chia seed has so much soluble fiber that it turns to a gel when mixed with water. It can thicken a smoothie up, but if you don't add enough liquid it can actually dehydrate you.

I've recently read that using the avocado pit is very good for you. You'll need a powerful blender; vita mix.

Here is a link that might be useful: Avocado Pit in Smoothies

I'm a big fan of raw foods - but not smoothies. After I had a gallstone last year, all I ate was raw foods.

I had a friend in high school that drank carrot juice before laying in the sun. It enhanced her tan.

Some other add-ins we like to use:
-homemade kefir (which is so much better for you than yogurt - milk kefir, water kefir, or coconut milk kefir) Freeze your kefir (or yogurt) for about an hour before making your smoothie.

-wheatgrass juice (grown and juiced at home)

-pumpkin puree

-oats (or leftover oatmeal or other cooked cereal)

-herbal teas, Kombucha, Rejuvelac (fermented wheat/water)

-grated ginger

-homemade nut and seed milks

-high-maize resistant starch (exceptional fiber)

-coconut flour (another great fiber)

-chardonnay grape seed flour (high-protein, fiber, and antioxidant properties and also thickens)

-nut and seed butters

-protein powder

-Crystal Light (powdered drink mix) - who knew?. I have a friend who can't consume fruit juice or fruit, so she flavors her smoothies with Crystal Light.

-Another flaxmeal fan - we always add it to smoothies.

-I add chia seed gel (water + chia seeds), instead of dry chia seeds.

-I make coconut milk (from Wilderness Family Naturals Powdererd Coconut Milk - same stuff I use to make coconut milk kefir) and will freeze it for an hour before making a smoothie with it.

-How about a nighttime smoothie:
warm milk
chamomile tea
pinch of nutmeg (induces sleep)
almond meal
cherries (good for mental fatigue and stress)

-Hot weather smoothie - Lassi
One part kefir (use the whey separated from kefir for a high-protein drink) or yogurt with 4 parts water.
Add sweetener-of-choice and a drop of rosewater.

-Grainlady

I made a smoothie this morning with fresh orange juice, a cup of blueberries and 6 cups of baby spinach. It was awesome. :) I love raw foods. I have a Vitamix so I throw in all sorts of things. I prefer to juice my carrots though.